Kernel source changes:
- Added xTaskNotifyStateClear() API function.
- Added the GCC Cortex-R port (existed for a while) into the main download.
- Improved the IAR RL78 port's handling of different memory model combinations.
- Removed some compiler warnings in heap_5.c.
Demo app changes:
- Added example use of xTaskNotifyStateClear() to the TaskNotify standard demo tasks.
Correct the header comments in het.c and het.h (RM48/TMS570 demo) which were corrupt.
Correct version numbers in RX63N Renesas compiler demo.
Ensure stacks set up for tasks in the RX200 port layer end on 8 byte boundaries (was 4, which didn't matter but didn't match the definition).
Replaced unqualified (unsigned) in calls to standard functions with (size_t).
